The objectives of the project are: 1. To pursue further the purification of the thyroid component homologous to LATS. 2. To obtain further understanding of the mode o action of LATS in the thyroid. 3. To establish a competitive protein-binding assay for LATS. 4. To try to measure variation in immune-competence throughout the course of Graves' disease, looking for changes coinciding with remission or relapse of hyperthyroidism. 5. To test the possible role of emotion in the formation of LATS by experimental production of a thyroid-stimulating antibody in animals subjected to stressful stimuli, or so treated as to mimic a possible emotion-induced state of thyroid hyperfunction. 6. Largely explored in 1972-73, to continue to test pituitary function in Graves' disease by measuring the concentration of thyrotropin and of prolactin in serum in response to injection of thyrotropin-releasing hormone. 7. To gain understanding of the control of thyroid function by studies of abnormalities developing in transplantable bovine thyroid tumours in rats.